a(n) = (1/2)*Sum_{j=0..2^n-1} j^(n-1) for n>=1.
A140048
a(n) = (1/2)*Sum_{j=0..2^n-1} j^(n-1) for n>=1.
Terms
- a(0) =1a(1) =3a(2) =70a(3) =7200a(4) =3098760a(5) =5461682688
External references
- oeis: A140048
A140048
a(n) = (1/2)*Sum_{j=0..2^n-1} j^(n-1) for n>=1.